package cn.hdu.liang.ch2;

import java.util.Set;
import java.util.TreeSet;

public final class Planets {
    private final Set<String> planets = new TreeSet<>();

    public Planets() {
        planets.add("111");
        planets.add("222");
        planets.add("333");
        planets.add("444");
        planets.add("555");
    }

    public boolean isPlanets(String planetName) {
        return planets.contains(planetName);
    }
}
